Digital video cassette recorder for preventing picture distortion during search and method for processing picture using the same

ABSTRACT

A digital video cassette recorder capable of preventing a picture from being distorted during a search, and a method for processing a picture according to the same are provided. The digital video cassette recorder includes a search command applier, a reproduction unit for outputting data reproduced in a normal mode according to a fourth control signal, a switch for selecting reproduced data output by the reproduction unit for a predetermined time according to a first control signal, a memory for storing the image data which is reproduced at the normal mode and output from the switch, a display for displaying the image data stored in the memory according to a second control signal, a capstan motor for converting a traveling speed of a tape in accordance with a normal reproduction mode or a search mode according to a third control signal, and a controller for outputting the fourth, first, second and third control signals for controlling the reproduction unit, the switch, the display and the capstan motor, respectively, when a search command is provided by the search command applier. As a result, picture distortion occurring on the display during search can be prevented.

CLAIM OF PRIORITY

[0001] This application makes reference to, incorporates the sameherein, and claims all benefits accruing under 35 U.S.C. §119 from anapplication for DIGITAL VIDEO CASSETTE RECORDER FOR PREVENTING PICTUREDISTORTION DURING SEARCH AND METHOD FOR PROCESSING PICTURE USING THESAME earlier filed in the Korean Industrial Property Office on the ^(th)of July 1997 and there duly assigned Serial No. 30653/1997.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present invention relates to a digital video cassetterecorder, and more particularly, to a digital video cassette recorderfor preventing picture distortion during search, and a method forprocessing a picture using the same.

[0004] 2. Related Art

[0005] Analog video cassette recorders adopt a consecutive recordingmethod, but digital video cassette recorders adopt a non-consecutiverecording method. Thus, the digital video cassette recorder displays anon-recognizable image, (i.e., an image signal whose image pixels arenot arranged) on its screen, while image data recorded in a recordingmedium is searched.

[0006] The digital video cassette recorder has a search mode and anormal reproduction mode. The digital video cassette recorder cannotreproduce a picture having the plurality of a normal picture in thesearch mode, since it scans more tracks at a time than in the normalreproduction mode. Accordingly, image data which is difficult for ahuman to recognize is displayed during the search mode.

[0007] The following patents are considered to be representative of theprior art, and are burdened by the disadvantages set forth herein: U.S.Pat. No. 5,583,936 to Wonfor et al., entitled Video Copy ProtectionProcess Enhancement To Introduce Horizontal And Vertical PictureDistortions, U.S. Pat. No. 5,452,096 to Ito, entitledRecording/Reproducing Apparatus Wherein The Same Frame Of A Video SignalIs Repeatedly Read Out Of A Memory To Produce Special Effects, U.S. Pat.No. 5,179,479 to Ahn, entitled Method Of High Speed Searching For ADesired Tape Portion In A Digital Audio Tape Recorder, U.S. Pat. No.5,748,332 to Lee, entitled Video Repeat Reproduction Method AndApparatus, U.S. Pat. No. 5,233,485 to Yang, entitled Index Search MethodAnd system Thereof For Digital Video Cassette Tape Recorder, U.S. Pat.No. 5,406,381 to Han, entitled Character-Displayed Index Search SystemAnd Method, U.S. Pat. No. 5,510,889 to Kim, entitled Method OfMulti-Speed Recording-Reproducing A Video Signal 1 Digital VideoCassette Recorder, U.S. Pat. No. 5,523,896 to Park, entitled VariableSpeed Reproducing Apparatus For A Digital Video Cassette Recorder, U.S.Pat. No. 5,528,382 to Kato et al., entitled Reproduction Apparatus ForVideo Signals Accompanied By Control Information, U.S. Pat. No.5,587,789 to Lee et al., entitled Apparatus And Method For ControllingRecording And Reproduction In Digital Video Cassette Tape Recorder, U.S.Pat. No. 5,479,265 to Kim et al., entitled Video Data RecordingApparatus For Digital Video Cassette Recorder, U.S. Pat. No. 5,418,623to Park, entitled Method Of Recording And Reproducing A Video SignalWith Improved Quality During Variable Speed Operation, and U.S. Pat. No.5,675,693 to Kagoshima, entitled Video Signal Reproducing Apparatus WithPlural Search Functions.

SUMMARY OF THE INVENTION

[0008] To solve the above problem, an object of the present invention isto provide a digital video cassette recorder which prevents picturedistortion during search by scanning some frames in a normal mode anddisplaying the scanned frames on a screen before execution of a searchoperation, and by simultaneously controlling the search operation to beexecuted in a search mode.

[0009] It is another object of the present invention to provide apicture processing method using the technique of the above digital videocassette recorder.

[0010] To accomplish the first object, there is provided a digital videocassette recorder which includes: a search command applier; areproduction unit for outputting data reproduced at a normal modeaccording to a fourth control signal; a switch for selecting reproduceddata output by the reproduction unit for a predetermined time accordingto a first control signal; a memory for storing the image data which isreproduced in the normal mode and output from the switch; a display fordisplaying the image data stored in the memory according to a secondcontrol signal; a capstan motor for converting the traveling speed of atape depending on a normal reproduction mode or search mode according toa third control signal; and a controller for outputting the fourth,first, second and third control signals for controlling the reproductionunit, the switch, the display and the capstan motor, respectively, whena search command is applied from the search command applier. Thepredetermined time mentioned above is the time for normally reproducinga predetermined number of frames.

[0011] To accomplish the second object, there is provided a method ofprocessing a screen picture during search, comprising the steps of: (a)applying a search command; (b) reproducing a predetermined number offrames in a normal mode; (c) storing image data reproduced in the normalmode; (d) executing search operation simultaneously while displaying thestored image data; (e) preventing reproduced data from being displayedand displaying searched data instead if desired image data is searched;and (f) determining whether display of the searched data is completed,and whether the search operation will continue. If the display of thesearched data is completed and a new search is to continue in step (f),the steps (d) to (f) are repeated. Also, if the display of the searcheddata is completed and a new search is to continue in step (f), the steps(b) to (f) are repeated. In addition, the searching step (d) comprisesthe steps of: converting a traveling speed of a tape to a travelingspeed used during the search; and preventing data reproduced during thesearch from being displayed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation of the invention, and many of theattendant advantages thereof, will be readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings in which like reference symbols indicate the same or similarcomponents, wherein:

[0013]FIG. 1 is a block diagram showing the configuration of a digitalvideo cassette recorder according to the present invention;

[0014]FIG. 2 is a detailed block diagram of the reproducing unit shownin FIG. 1;

[0015]FIG. 3 is a flowchart illustrating a method of processing apicture during search according to a first embodiment of the presentinvention; and

[0016]FIG. 4 is a flowchart illustrating a method of processing apicture during search according to a second embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring to FIG. 1, a digital video cassette recorder includes areproduction unit 100, a switch 102, a memory 104, a display 106, acapstan motor 108, a controller 10 and a search command applier 112.

[0018] Referring to FIG. 2, the reproduction unit 100 includes areproduction head 10, an amplifier 12, an equalizer 14, an inversediscrete cosine transformer (IDCT) unit 16, an error corrector 18 and anextension unit 20. Unit 100 outputs reproduced data for a predeterminedtime according to a fourth control signal output by the controller 110.

[0019] The switch 102 selects the reproduced data output from thereproduction unit 100 for a predetermined time according to a firstcontrol signal output by the controller 110. That is, the switch 102selects the reproduced data if the first control signal is a high level,and interrupts selection of the reproduced data if the first controlsignal is a low level.

[0020] The memory 104 stores image data which is reproduced in a normalreproduction mode and output from the switch 102.

[0021] The display 106 displays the image data stored in the memory 104according to a second control signal output by the controller 110. Thatis, the display 106 displays the image data stored in the memory 104 ifthe second control signal is a high level, and displays searched imagedata if the second control signal is a low level.

[0022] The capstan motor 108 determines the traveling speed of the tapedepending on a normal reproduction mode or search mode according to athird control signal output by the controller 110. That is, if the thirdcontrol signal is a high level, the capstan motor 108 spins at a speedappropriate for the normal reproduction mode. If the third controlsignal is a low level, the capstan motor 108 spins at a speedappropriate for the search mode.

[0023] The controller 110 provides the fourth, first, second and thirdcontrol signals for controlling the reproduction unit 100, the switch102, the display 106 and the capstan motor 108, respectively.

[0024] That is, the controller 110 controls the reproduction unit 100and the capstan motor 108 to output normal reproduced data for apredetermined time when a search command is applied from the searchcommand applier 112. The controller 110 controls the switch 102 toselect reproduced data output by the reproduction unit 100. The term“predetermined time” denotes a period during which reproduced data oftwo or three frames can be output. The controller 110 controls thedisplay 106 to display the reproduced data read from the memory 104, andsimultaneously controls the capstan motor 108 to rotate the tape at asearch mode speed.

[0025] The operation of the device shown in FIG. 1 will now bedescribed. After a search command is provided by the search commandapplier 112, the controller 110 controls the capstan motor 108 tomaintain the traveling speed at a value at which normal reproduction isconducted, and controller 110 controls the reproduction unit 100 tooutput normal reproduced data by operating some frames (e.g., two orthree frames) at the normal reproduction mode. Also, the controller 110controls the switch 102 to select data reproduced by the reproductionunit 100. At this time, the memory 104 stores the reproduced data outputvia the switch 102.

[0026] The controller 110 also controls the display 106 to display thenormal reproduced data stored in the memory 104, controls the switch 102to connect or disconnect the normal reproduced data, and controls thecapstan motor 108 to rotate a tape at a predetermined search mode speed.

[0027] When the search command is provided, image data having someframes reproduced during the normal reproduction mode is continuouslydisplayed on the display 106, and a search operation is conductedsimultaneously so that the user does not see distorted picture duringthe search. When desired searched data is detected, the searched imagedata is displayed on the display 106.

[0028] In the above-described embodiment, extended reproduced data isselected by the switch 102 for a predetermined time. After thepredetermined time elapses, the switch 102 interrupts the selection ofthe reproduced data. However, the selection and non-selection of areproduced signal using the switch 102 can be performed on reproduceddata output from other blocks of the reproduction unit 100. The memory104 can be an error-correction memory (not shown) or a de20 shufflingmemory (not shown).

[0029] A picture displayed on the display 106 during a search can beupdated by performing selection or non-selection via the switch 102 inunits of a predetermined number of reference frames.

[0030]FIG. 3 is a flowchart illustrating a method for processing ascreen picture during search according to a first embodiment of thepresent invention.

[0031] In the method for processing a screen picture during a search asshown in FIG. 3, data reproduced in the normal reproduction mode whenthe search begins is stored only one time, and the stored normalreproduced data is continuously displayed during the search. Aftersearched data is detected, the reproduced data being displayed isconverted to the searched data, and the searched data is then displayed.Accordingly, the image data reproduced in the normal mode upon theinitiation of the search continues to be displayed until the search isended.

[0032] Hereinbelow, the flowchart shown in FIG. 3 will be described inmore detail.

[0033] A search command is provided in step 300.

[0034] A predetermined number of frames is reproduced in a normal modein step 302.

[0035] Image data reproduced in the normal mode is stored in apredetermined memory in step 304.

[0036] The stored image data is displayed on a display in step 306, andthe search is conducted in step 308. In order to execute the search, thecapstan motor 108 (FIG. 1) spins at a search speed, and data producedduring the search is prevented from being displayed on the display 106.

[0037] A determination of whether desired image data is detected duringthe search is made in step 310 (FIG. 3). If the desired image data isnot detected, step 308 is repeated; if the desired image data isdetected, the reproduced data being displayed is eliminated and thesearched data is displayed instead in step 312.

[0038] A determination of whether display of the searched data iscompleted is made in step 314. If display of the searched data isfinished a determination is made in step 316 as to whether the search isto continue. If it is determined that the search is not to continue, thesearch is ended. If it is determined that the search continues, thestored image data is displayed in step 306, and steps 308 thru 316 areperformed.

[0039]FIG. 4 is a flowchart illustrating a method for processing ascreen picture during search according to a second embodiment of thepresent invention.

[0040] In the method of processing a screen during search as shown inFIG. 4, whenever the search continues, data reproduced in a normal modeis stored, and then the stored normal reproduced data is displayedduring the search. Thus, whenever the search resumes, the normalreproduced image data is changed and displayed.

[0041] Now, the method shown in FIG. 4 will be described in more detailas follows.

[0042] A search command is provided in step 400.

[0043] A predetermined number of frames is reproduced in a normal modein step 402.

[0044] Image data reproduced in the normal mode is stored in apredetermined memory in step 404.

[0045] The stored image data is displayed on a display in step 406, andthe search is conducted in step 408. In order to execute the search, thecapstan motor 108 (FIG. 1) spins at a search speed, and data reproducedduring the search is prevented from being displayed on the display 106.

[0046] A determination as to whether desired image data is detectedduring search is made in step 410. If the desired image data is notdetected, the step 408 is repeated; and if the desired image data isdetected, the reproduced data being displayed is eliminated and thesearched data is displayed instead in step 412.

[0047] A determination as to whether display of the searched data iscompleted is made in step 414. If display of the searched data isfinished, a determination is made in step 414 as to whether the searchwill continue. If it is determined that the search will no longercontinue, the search is ended. If it is determined that the search willcontinue, steps 402 thru 416 are repeated.

[0048] According to the present invention described above, screenpicture distortion occurring on the display during the search can beprevented.

[0049] It should be understood that the present invention is not limitedto the particular embodiment disclosed herein as the best modecontemplated for carrying out the present invention, but rather that thepresent invention is not limited to the specific embodiments describedin this specification except as defined in the appended claims.

What is claimed is:
 1. A digital video cassette recorder comprising:command means for providing a search command; reproduction means foroutputting data reproduced in a normal mode of operation in response toa fourth control signal; switch means for selecting the data output bythe reproduction means for a predetermined time, in response to a firstcontrol signal; memory means for storing the data output selected bysaid switch means; display means for displaying the data output storedin said memory means in response to a second control signal; capstanmotor means for adjusting a traveling speed of a tape in accordance witha normal reproduction mode or a search mode in response to a thirdcontrol signal; and controller means for outputting the fourth, first,second and third control signals for controlling said reproductionmeans, said switch means, said display means and said capstan motormeans, respectively, when the search command is provided by said commandmeans.
 2. The digital video cassette recorder as claimed in claim 1,wherein said predetermined time is a time for normally reproducing apredetermined number of frames.
 3. A method of processing a screenpicture during a search, comprising the steps of: (a) providing a searchcommand; (b) reproducing a predetermined number of frames in a normalmode of operation; (c) storing image data reproduced in the normal modeor operation; (d) executing the search to detect desired image datawhile displaying the stored image data; (e) preventing reproduced datafrom being displayed and displaying detected data instead when desiredimage data is detected; and (f) determining whether display of thedetected data is completed and whether the search operation willcontinue; wherein, when the display of the searched data is completedand the search operation is to continue, said steps (d) to (f) arerepeated.
 4. The method of processing a screen picture during a searchas claimed in claim 3, wherein when the display of the searched data iscompleted and the search operation is to continue, said steps (b) to (f)are repeated.
 5. The method of processing a screen picture during asearch as claimed in claim 4, wherein said step (d) comprises the stepsof: converting a traveling speed of a tape to a traveling speed usedduring the search; and preventing data reproduced during the search frombeing displayed.
 6. The method of processing a screen picture during asearch as claimed in claim 3, wherein said step (d) comprises the stepsof: converting a traveling speed of a tape to a traveling speed usedduring the search; and preventing data reproduced during the search frombeing displayed.
 7. A digital video cassette recorder, comprising:command means for providing a search command; reproduction means foroutputting data reproduced in a normal mode of operation in response toa first control signal; switch means for selecting the data output bythe reproduction means for a predetermined time in response to a secondcontrol signal; motor means for adjusting a traveling speed of a tape inaccordance with a normal reproduction mode and a search mode,respectively, in response to a third control signal; and controllermeans for providing said first, second and third control signals forcontrolling said reproduction means, said switch means and said motormeans, respectively, when the search command is provided by said commandmeans.
 8. The digital video cassette recorder as claimed in claim 7,further comprising output means for outputting the data selected by saidswitch means.
 9. The digital video cassette recorder as claimed in claim8, wherein said output means comprises a memory for storing the dataoutput selected by said switch means.
 10. The digital video cassetterecorder as claimed in claim 8, wherein said output means comprises adisplay unit for displaying the data output selected by said switchmeans.
 11. The digital video cassette recorder as claimed in claim 10,wherein said control means provides a fourth control signal forcontrolling the display unit.
 12. A method for processing a screenpicture during a search, comprising the steps of: providing a searchcommand; reproducing a predetermined number of frames in a normal modeof operation; storing, image data reproduced in the normal mode ofoperation; executing the search to detect desired image data whiledisplaying the stored image data; preventing the data reproduced in thenormal mode of operation from being displayed and displaying thedetected desired image data instead when the desired image data isdetected; and determining whether display of the searched data iscompleted; and when the display of the search data is not completed,displaying the searched data.
 13. The method of processing a screenpicture during a search as claimed in claim 12, further comprising thestep of: when the display of the searched data is completed, determiningwhether the search is to continue.
 14. The method of processing a screenpicture during a search as claimed in claim 13, further comprisingreturning to the step of storing the image data reproduced in the normalmode of operation when the search is to continue.
 15. The method ofprocessing a screen picture during a search as claimed in claim 12,wherein the step of executing the search to detect the desired imagedata while displaying the stored image data comprises the steps of:converting a traveling speed of a tape to a traveling speed used duringthe search; and preventing data reproduced during the search from beingdisplayed.